Researchers in the US have also started finding evidence that the virus was infecting and killing people earlier than the country's first reported cases.
The samples had all initially been collected to detect flu using PCR tests, the same genetic screening process that can also be used to detect the presence of the novel coronavirus in patients infected at the time the sample is collected.
Yves Cohen, head of resuscitation at the Avicenne and Jean Verdier hospitals in the northern suburbs of Paris, told BFM TV that scientists had retested samples from 24 patients treated in December and January who tested negative for the flu.
A French hospital which has retested old samples from pneumonia patients discovered that it treated a man who had COVID-19 as early as Dec 27, nearly a month before the French government confirmed its first cases.
France, which has seen almost 25,000 people die from the virus since March 1, confirmed its first three COVID-19 cases on Jan 24, including two patients in Paris and another in the southwestern city of Bordeaux.
Cohen said it was too early to know if the patient whose Dec 27 test was COVID-19 positive is France’s “patient zero”. Knowing who was the first is critical to understanding how the virus spread.
采访视频截图"One sample was positive taken from a 42-year-old man born in Algeria, who lived in France for many years, and worked as a fishmonger," the team wrote. "His last trip was in Algeria during August 2019."
There's new evidence that the coronavirus may have been in France weeks earlier than was previously thought.
“He was sick for 15 days and infected his two children, but not his wife, who works in a supermarket.
“He was amazed, he didn’t understand how he had been infected. We put the puzzle together and he had not made any trips. The only contact that he had was with his wife.”
Cohen said the patient had survived and that a first investigation to trace the first contamination has been carried out.
If verified, this finding would show that the virus was already circulating in Europe at that time -- well before the first known cases were diagnosed in France or hotspot Italy.
The French team looked at people admitted to the hospital with flu-like illness between December 2 and January 16 who were not ultimately diagnosed with influenza. They tested frozen samples from those patients for coronavirus.
“Of the 24, we had one who was positive for COVID-19 on Dec 27,” he told the news channel on Sunday.
Each sample was retested several times to ensure there were no errors, he added.
"Identifying the first infected patient is of great epidemiological interest as it changes dramatically our knowledge regarding SARS-COV-2 and its spreading in the country. Moreover, the absence of a link with China and the lack of recent travel suggest that the disease was already spreading among the French population at the end of Dec, 2019," they wrote.